Cam gear missing the tips of some teeth! - PeachParts Mercedes-Benz Forum

New2MB · #1 11-03-2005, 08:02 PM

I decided to change the timing chain on my car because it has 167K and I have no idea if it was ever changed. So I take off the valve cover to inspect everything and I notice that several of the cam gear teeth are missing the tips. It appears that the tips broke off leaving a jagged edge.

I have two concerns now; do I bother trying to find the teeth (I don't have a clue how I would find them) since the engine is running good and can I change the cam gear by just pulling it off the cam and putting a new one on? I just wanted a new chain! Arrrgh.

boneheaddoctor · #2 11-03-2005, 08:04 PM

how many miles on the engine?

New2MB · #3 11-03-2005, 08:08 PM

Quote:

Originally Posted by boneheaddoctor

how many miles on the engine?

167,000 miles of lackluster maintenance.

boneheaddoctor · #4 11-03-2005, 08:12 PM

Quote:

Originally Posted by New2MB

167,000 miles of lackluster maintenance.

I ask becasue if they wore enough to break off the crank pully likely looks as bad...

however I doubt the cost and effort to replace that one too will be worth it...definately replace the cam sprocket and the timing chain along with the tensioner, depends on how many miles you expect it to last if you want to do the crank sprocket too.

Seriously worn sprockets will wear a chain prematurely......something to think about...

New2MB · #5 11-03-2005, 08:15 PM

Quote:

Originally Posted by boneheaddoctor

I ask becasue if they wore enough to break off the crank pully likely looks as bad...

however I doubt the cost and effort to replace that one too will be worth it...definately replace the cam sprocket and the timing chain along with the tensioner, depends on how many miles you expect it to last if you want to do the crank sprocket too.

I'm putting alot of time into the car so I might be willing to pull the engine to get the crank sprocket. What do you think the odds are of the crank sprocket being damaged? Ever heard of anyone doing it with the engine in the car or is that impossible?

boneheaddoctor · #6 11-03-2005, 08:19 PM

Quote:

Originally Posted by New2MB

I'm putting alot of time into the car so I might be willing to pull the engine to get the crank sprocket. What do you think the odds are of the crank sprocket being damaged? Ever heard of anyone doing it with the engine in the car or is that impossible?

never tried so I can't answer that....wait for a few opinions...Engatwork, LarryBible, Leathermang and Whunter are a couple that come to mind that have been inside these repeatedly....I trust their opinions...

New2MB · #7 11-03-2005, 08:49 PM

Quote:

Originally Posted by boneheaddoctor

never tried so I can't answer that....wait for a few opinions...Engatwork, LarryBible, Leathermang and Whunter are a couple that come to mind that have been inside these repeatedly....I trust their opinions...

Appreciate the honesty, thanks for the help.

boneheaddoctor · #8 11-03-2005, 08:51 PM

Quote:

Originally Posted by New2MB

Appreciate the honesty, thanks for the help.

In case you don't have a "REAL" manual try this site if you havent already. I don't consider Haynes a real manual.

http://skinnerbox.steaky.org

boneheaddoctor · #9 11-04-2005, 08:19 AM

Bumping this since the pros have missed it...

dannym · #10 11-04-2005, 08:32 AM

Just out of curiosity, how much chain stretch have you measured?
167K isn't really a whole lot for that chain. A visual inspection of the chain and an accurate measurement of stretch will give you an idea of where you stand instead of just throwing parts at it.
There is tons of information on timing chains in the archives. Here are a few to get you started:

http://www.peachparts.com/shopforum/showthread.php?t=96572

617 '05' Camshaft Specifications:

Q on timing chain stretch...

W123 Timing Chain Stretch

Whether you decide to replace the chain or just add an woodruff key at least now you'll be informed.

Quote:

and can I change the cam gear by just pulling it off the cam and putting a new one on? I just wanted a new chain! Arrrgh.

You don't need to remove the cam to replace the sprocket. There are directions in that on-line manual BHD posted.

Danny

Pete Burton · #11 11-04-2005, 08:44 AM

I hesitate to comment because my experience lies with the 617, but I expect some similarity. While it might be possible to do that in the car, I wouldn't want to. On the 617, the oil pump chain is outboard of the timing chain. Do you have another vehicle to drive for a few months? Do you have at least a 1/2 decent place to work with a poured or paved surface? If so, I'd pull the powertrain in one piece. I've done that at least 3 times and it's not too bad.

No matter what, I'd drop the lower oil pan and inspect everything. You should be able to see the crank sprocket. It's pitch diameter is exactly half of the cam sprocket. Check the oil pump sprockets and chain too.

New2MB · #12 11-04-2005, 09:18 AM

Quote:

Originally Posted by Pete Burton

I hesitate to comment because my experience lies with the 617, but I expect some similarity. While it might be possible to do that in the car, I wouldn't want to. On the 617, the oil pump chain is outboard of the timing chain. Do you have another vehicle to drive for a few months? Do you have at least a 1/2 decent place to work with a poured or paved surface? If so, I'd pull the powertrain in one piece. I've done that at least 3 times and it's not too bad.

No matter what, I'd drop the lower oil pan and inspect everything. You should be able to see the crank sprocket. It's pitch diameter is exactly half of the cam sprocket. Check the oil pump sprockets and chain too.

This is my project car and I have the facilities to pull the powertrain. In fact I have to pull the tranny for a rebuild anyway. I didn't want to do it but what the hell, it's been a few years anyway.

That online manual is all broken links, at least for my model.

Pete Burton · #13 11-04-2005, 09:42 AM

try this link for manual: http://mb.braingears.com

New2MB · #14 11-04-2005, 10:35 AM

So if I was really stubborn about pulling the engine, does anyone have any idea what the odds are of the crank gear also being damaged? Some people I talked to are telling me that it is alot less likely to be damaged than the cam gear. If I pull the engine then I will obviously have to rebuild the whole thing ('cause it's already out) and I wouldn't mind putting a few more miles on it before that. Opinions welcomed.

boneheaddoctor · #15 11-04-2005, 10:44 AM

Quote:

Originally Posted by New2MB

So if I was really stubborn about pulling the engine, does anyone have any idea what the odds are of the crank gear also being damaged? Some people I talked to are telling me that it is alot less likely to be damaged than the cam gear. If I pull the engine then I will obviously have to rebuild the whole thing ('cause it's already out) and I wouldn't mind putting a few more miles on it before that. Opinions welcomed.

I like to use a motorcycle analogy here....(from visibility stance)

sprockets wear...you need to replace them when they do as they will kill a good new chain in short order....

if one has worn enough for tips to break odds are good the other one is pretty well worn too.

The crank sprocket will have had twice as much chain pass by it than the cam....(being the cam roates at 1/2 crank speed , but it sees more oil......)